Dozens of rebels and Syrian government troops have reportedly been killed in fighting near a police academy in Syria's northern province of Aleppo.

The London-based Observatory for Human Rights said at least 26 rebel fighters and some 40 soldiers were killed during clashes on February 25-26.

Rebels say government forces have turned the police academy into a military base to shell opposition-held areas.

Also on February 26, the observatory said more than 140 people, including dozens of women and children, were killed in missile strikes by the Syrian government in and near the city of Aleppo last week.

The United Nations says more than 70,000 people have been killed since the uprising against Syrian President Bashar al-Assad began in March 2011.